Micromechanical behavior of single-crystal superalloy with different crystal orientations by microindentation

Abstract

In order to investigate the anisotropic micromechanical properties of single-crystal nickel-based superalloy DD99 of four crystallographic orientations, (001), (215), (405), and (605), microindentation test (MIT) was conducted with different loads and loading velocities by a sharp Berkovich indenter. Some material parameters reffecting the micromechanical behavior of DD99, such as microhardness H, Young's modulus E, yield stress Ω γ, strain hardening component n, and tensile strength Ω b, can be obtained from load-displacement relations. H and E of four different crystal planes evidently decrease with the increase of h. The reduction of H is due to dislocation hardening while E is related to interplanar spacing and crystal variable. Ω γ of (215) is the largest among four crystal planes, followed by (605), and (001) has the lowest value. n of (215) is the lowest, followed by (605), and that of (001) is the largest. Subsequently, a simplified elastic-plastic material model was employed for 3D microindentation simulation of DD99 with various crystal orientations. The simulation results agreed well with experimental, which confrmed the accuracy of the simplifed material model.